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. Author manuscript; available in PMC: 2014 Nov 14.
Published in final edited form as: EcoSal Plus. 2012 Nov;5(1):10.1128/ecosalplus.7.2.5. doi: 10.1128/ecosalplus.7.2.5

FUGURE 6.

FUGURE 6

Bidirectional mechanism of mismatch repair. The mismatch (carets) is bound by MutS (pierced circle) and MutL (red circles) leading to activation of the MutH endonuclease which can cleave either side of the mismatch. The mechanism leading to MutH endonuclease activation is not known. After cleavage, MutH is displaced by UvrD helicase which unwinds the DNA towards the mismatch. Unwinding in the 5′ to 3′ direction results in digestion of the single-stranded end by ExoVII or RecJ. Unwinding in the opposite direction requires ExoI, ExoVII or ExoX nucleases. The gap produced by excision is filled by DNA polymerase III holoenzyme. The resultant nick is sealed by DNA ligase, and Dam methylates the GATCs on the unmethylated strand, preventing further repair. The Figure has been modified from reference (53).